The scope of drug dependence in the U.S., and the urgency of preventing its continued adverse effects on both drug-dependent individuals and the public's health and welfare, require the development and evaluation of innovative interventions. Particularly important is the design and testing of interventions which attempt to overcome barriers to enhancing the motivation of drug-abusing individuals to change and, if needed, facilitating their entry into supportive programs. The proposed study will offer the first opportunity to evaluate with a drug-involved population a highly successful motivational enhancement intervention that has been studied with alcohol consumers. Termed the "Drinker's Check-up", this intervention offers a confidential opportunity for an individual to discuss with a professional his/her pattern and history of drinking, associated benefits and costs, and the individual's thoughts about the possible reasons for continuing or changing the drinking behavior. The researchers found that a substantial percentage of those who sought the check-up were abusive drinkers. Moreover, a substantial percentage used the opportunity of discussing their situation to commit themselves to initiating change. The proposed studies have the following aims: 1) to develop a Marijuana Check-Up (MCU) based on procedures and findings from the Drinkers Check-up and previous treatment research with marijuana-dependent adults, 2) refine the assessment and therapeutic techniques based on results from an initial study with 40 adult marijuana users, 3) test the efficacy of the MCU in comparison with a delayed-treatment control group using 200 adult marijuana users recruited from the general population, and 4) identify demographic, psychological, social, and intervention predictors of reduced marijuana use and treatment engagement across the 12 months following the subjects participation in the MCU.